This invention is directed to a baler (commonly known as "round baler") for forming cylindrical bales and having a bale-forming chamber defined by a plurality of belts trained about a plurality of rolls and, more particularly, to an automatic mechanism for wrapping twine around bales formed in the chamber.
Semiautomatic twine wrapping machanisms for round balers for agricultural crops are well known. One commercially available wrapping mechanism is similar to that disclosed in U.S. Pat. Nos. 3,894,484 and 3,913,473. The mechanism comprises generally a hydraulically driven twine arm which is movable back and forth in front of an entrance to the bale-forming chamber. Initiation and termination of the twine wrapping cycle is manually controlled. The rate of advance of the arm transversely of the bale-forming chamber is subject to manual control by the adjustment of the flow control valve in the hydraulic circuit. Following extended commercial use, certain disadvantages for this mechanism have been noted. First, it is desirable to provide automatic (rather than semiautomatic) initiation and termination of the twine-wrapping cycle. Heretofore the operator monitored a bale size gauge on the front of the baler from the operator's position on the tractor pulling the baler. When the bale reached the desired size, the operator then continued baling and pulled a hydraulic lever to actuate movement of the twine arm from a first side of the baler to the second. When the twine is fed with the crop material into the bale-forming chamber, the tractor is stopped to discontinue feeding crop into the chamber. The lever is retained in its shifted position until the twine arm reached the second side and held there to allow one or more turns of twine to go around the end of the bale. Then, the hydraulic lever is shifted to reverse the hydraulic drive so that the twine arm is driven back to the first side of the baler. The rate of movement of the twine arm from the second to the first side of the baler and therefore the number of wraps of twine around the bale is controllable by adjustment of the flow control valve in the hydraulic circuit. The rate of flow is adjusted such that at least one full wrap of twine is formed around the end of the bale. The twine is then automatically cut. With the automation of such procedure, the burden on the operator of monitoring the operation of the machine behind him from his position in front of the tractor would, of course, be relieved.
Secondly, it has been found that the procedure for threading twine through the twine arm, which is an elongated tubular member pivoted at one end, is unduly tedious. To thread the twine, it is necessary to push the twine through the elongated tube until it reaches the free end of the tube. Often the twine hangs in the tube and must be manually pulled through with the aid of a threading member, such as a stiff wire.
Thirdly, it was found that the prior art twine cutter mechanism required precision of manufacture, initial adjustment, and also required maintenance to ensure reliable cutting. The prior art twine cutter is actuated by the travel of the twine arm from the second to the first side of the baler which pivots an anvil into engagement with a knife with the twine disposed therebetween. Any overtravel of the twine arm provided excessive pressure to be exerted by the anvil on the knife edge, tending to dull or bend the knife edge.
It is also known to provide a fully automated twine-wrapping mechanism using a mechanical drive from the PTO to drive a pair of twine arms transversely of the bale-forming chamber. See, for example, U.S. Pat. No. 4,167,844.
Further, it is known to provide a fully automated twine-wrapping system using a spring drive for moving a single twine arm from a first side to the second side of the baler and a hydraulic drive for moving the twine arm from the second side back to the first side. See U.S. Pat. No. 4,150,614.
Accordingly, it is an object of this invention to provide an improved, fully automated hydraulically driven twine-wrapping mechanism.
Another object of this invention is to provide a simple, reliable twine-wrapping control mechanism which automatically controls the actuation of the hydraulic pump and control valve of the hydraulic drive means for the twine-dispensing mechanism.
Another object of the invention is to provide an automatic hydraulically driven twine-wrapping mechanism with a hydraulic drive means including a clutch for permitting the twine arm to dwell and provide additional wraps of twine around one end of the bale.
Another object is to provide a hydraulically driven twine-wrapping mechanism which has a unitary relatively long twine dispensing arm for a small width round baler and which is operable to provide additional wraps of twine around each end of the bale.
Another object of the invention is to provide a twine-wrapping mechanism with a twine arm permitting simplified threading of the twine therethrough.
Still another object of the invention is to provide a twine tensioner permitting simplified disposition of the twine therethrough.
Still another object of the invention is to provide an improved twine cutter which has an improved life and requires lower precision of manufacture, adjustment and maintenance.